Measurements of dilepton channels at LHCb

Plews, Jonathan (2022). Measurements of dilepton channels at LHCb. University of Birmingham. Ph.D.

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Abstract

Measurements of the Drell-Yan cross-section provide insight into the structure ofthe proton. Measurements are made at LHCb, via the dimuon channel, as a double differential cross-section with respect to dimuon mass and rapidity, and with respectto dimuon mass and transverse momentum in the ranges 4 < \(m_{\mu\mu}\) < 120GeV, 2.5 < \(y\) < 4.5 and 1< \(p_{T}\) < 500GeV. Dimuon candidates are selected from 1.63 fb^{-1} of data taken at LHCb in 2016 and fit as a function of minimum muon \(\sqrt{\chi^{2}_{IP}}\) using templates for components of the signal and the relevant backgrounds. A search for the lowest spin-triplet state of true muonium (\(\mu^{+}\mu^{-}\)) is also proposed. True muonium offers an opportunity to test standard model physics in a purely muonic system. It is suggested that decays of \(TM \rightarrow e^{+}e^{−}\) could be detected at LHCb, produced from the decays of \(\eta\rightarrow\gamma^{*}\gamma\), where \(\gamma^{*}\) mixes with \(TM\). Two searches are proposed, an inclusive search where only the dielectron pair is selected and an exclusive search where the photon is also selected and the \(\eta\) meson is reconstructed. It is shown that in order to discover true muonium to \(5\sigma\) significance, LHCb would be required to achieve reconstruction efficiencies of \(\varepsilon_{e^{+}e^{-}}\) > 20% and \(\varepsilon_{\gamma e^{+}e^{-}}\) > 12%, within the fiducial acceptance.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):